This invention relates to a method for improving fuel economy and emissions in high altitude conditions.
It has long been known that at high altitudes the conventional automobile engine operates at higher ratios of fuel to air, causing increased carbon monoxide exhaust emissions to be emitted and increasing fuel consumption. Tests by laboratories at high altitude conditions have shown that carbon monoxide emissions are more than twice those for the same engine operating at sea level conditions. This has caused severe air pollution problems at relatively high altitude locations such as Denver.
Late-model vehicles are being equipped with oxidizing catalytic converters to further reduce carbon monoxide and unburned hydrocarbons. More than one-half of these vehicles are adjusted to low fuel-air ratios to provide enough oxygen in the exhaust for catalytic conversion. At high altitudes the fuel-air ratio is affected such that the catalytic converters do not function properly, thereby greatly diminishing an important pollution control strategy.
Engines are designed and adjusted to optimize the carburetor fuel-air ratio and spark timing at sea level to provide the lowest fuel consumption commensurate with the exhaust emission standards imposed. This optimum fuel-air ratio is adversely altered by the effect of high altitudes on the carburetor and results in greater fuel consumption which intensifies an already critical energy shortage in the United States.
Additionally, more stringent standards are being imposed in coming years to reduce the carbon monoxide at high altitude conditions. The new standards imposed by this regulation are to correct for the altitude effect on emissions and fuel consumptions. However, these new standards only apply to post 1976 model vehicles which does not alleviate the problem of the many thousands of vehicles operating at high altitudes that will be in service for many years, producing high levels of air pollution with lower fuel economy.